Fuze arming device



FUZE ARMING DEVICE Filed Jan. 7, 1960 G an L'- M INVENTORS r f- FRANK c. HUTCHISON- k RICHARD w. RIPP W w|| |s F. T ETTS w B 5! 3 r 4 J. M xrrormsvs ate.

3,59,577 Patented Oct. 23, 1962 Fee FUZE ARMING DEVICE Frank C. Hutchison, Greenfield, N.H., Richard W. Stripp, Bound Brook, N.J., and Willis F. Tibbetts, Reading, Mass., assignors to the United States of America as represented by the Secretary of the Army Filed Jan. 7, 1960, Ser. No. 1,143 2 Claims. (Cl. 102-84) This invention relates to fuze arming devices for use in connection with artillery shells, and has for its principal object the provision of an improved arming device which is of relatively simple construction and is operated altogether in response to forces which are incident to its flight.

In the use of such fuze arming devices it is necessary that, when the fuze is combined with the shell, the shell cannot be detonated by rough handling. The safety of the gun crew also requires that the shell be maintained incapable of detonation until it reaches a certain point in its trajectory. In accordance with the present invention, these results are achieved (1) by utilizing the setback force incident to the acceleration of the device to delay the initiation of its operation and (2) by utilizing the centrifugal force generated by the spinning of the device to effect its operation.

The invention will be better understood from the following description when considered in connection with the accompanying drawings, and its scope is indicated by the appended claims.

Referring to the drawings:

FIG. 1 is a side view of the device with a cover removed to show the device in its unarmed condition,

FIG. 2 is a section taken on the line 22 of FIG. 1,

FIG. 3 is a section taken on the line 33' of FIG. 2 and showing parts of the device in their armed positions,

FIG. 4 is a section taken on the line 4-4 of FIG, 1, and

FIG. 5 is a section taken on the line 5-5 of FIG. 3.

As indicated by FIGS. 1 to 4, the device has a housing consisting of an inner body 6 and an outer body 1 which has an external thread for securing it in the shell to be fired. The primary means (not shown) for actuating the firing train exerts a force in the direction of the arrow 2, this force being applied to a detonator when it is rotated into alinement with a primer as hereinafter described.

As unbalanced rotor or ratchet wheel 3 is rotatably mounted in a journal 4 in the outer body 1 and a journal 5 in an inner body 6. The inner body 6 is secured to the outer body 1 by means of screws 7.

A detonator 8 is mounted in a hole 9 extending through the ratchet wheel 3 which is shown in FIG. 1 in its unarmed position, the axis of the hole 9 being out of line with the firing train. Thus, in the unarmed position, the solid portion 11 of the wheel 3 separates the primary means of actuation from a lead cup primer 12 in the outer body 1.

A pin 13 is movable into a recess or indentation 14 in wheel 3, being held in this recess by a compression spring 15. This spring is so designed that the pin 13 is not disengaged from the recess 14 by rough handling of the shell. Only when the outer body 1 is spun about its longitudinal axis at a speed such as would be encountered in a rifle barrel will the pin be thrown out of the recess by the centrifugal force acting on the pin 13.

During acceleration of the device, the resulting setback force generates so much friction between the pin 13 and the hole 14 surrounding it that the pin cannot move until the setback force decays. When this happens the pin moves outwardly, and the wheel 3 rotates clockwise until a detent pin 16 engages a hole 17 in the outer body 1. In that position, the axis 18 of the detonator 8 is alined with a hole 19 in the inner body 6 through which the primary means of actuating the firing train enters. As the lead cup primer 12 is on the same line, the firing train is in a condition to function.

The time required for wheel '3 to rotate from the unarmed position (FIG. 2) to the armed position (FIG. 3) is made such that the shell is at a suificient distance from the gun to ensure the safety of the gun crew. This is efiected by means of a pawl 20 which is reciprocated by engagement with the teeth 21 of the ratchet wheel. This pawl has a tang 22 which engages a slot 23 in an inertia disk 24 pivoted about a shaft 25 on the inner body 6. A stop 26 extending through an opening 28 in the inertia disk 24 limits the oscillations of this disk to a travel determined by the size of the hole. The inertia resistance of a disk 24 to reversing its direction alternately slows down the wheel 3 sufiiciently to produce the required delay in arming. A dust cover 27 is crimped into the outer body 1, and retains the inertia disk. In this way, the device is rendered safe from the viewpoint of both rough handling and the danger of explosion of the shell too near to the gun.

Operation of the present device is effected by a predetermined balance between setback force and centrifugal force. Both these forces act on the pin 13. Initially the setback force holds the pin against the ratchet wheel 3 so tightly that the centrifugal force is unable to overcome the friction between the wheel and pin. As the setback force decreases, the friction between the pin and wheel decreases. Eventually this decrease in friction reaches a value such that centrifugal force is able to move the pin 13 out of the recess 14. Thereupon the ratchet wheel 3 having its rotational axis displaced from the rotational axis of the fuze, is set into rotation by centrifugal force.

This rotation of the ratchet wheel 3 starts from the position indicated by FIGS. 1 and 2 which illustrate the unarmed condition of the fuze. In this position, the detonator 8 is out of alinement with the central opening 2 and the lead cup primer 12. As the ratchet wheel 3 rotates, the detonator 8 is brought into alinement with hole 2 and the lead cup primer 12. At this point it is stopped by engagement of the pin 16 in a recess inside the outer body 1. This puts the firing train in a condition to function.

During rotation of the ratchet wheel 3, its speed is regulated by the pawl 20, the tang 22 of which extends through a slot 23 in the inertia disk 24. The ratchet wheel functions to reciprocate this disk through an angle determined by the size of the slot 28 in which the stop 26 is located. As is well understood by those skilled in the art, the inertial resistance of the disk 24 to reversal in its direction of rotation functions to slow down the ratchet wheel and delay arming of the fuze.

We claim:

1. In a fuze arming device, the combination of an outer body having spaced apart closures with alined central openings,

a primer cup located in one of said openings,

an inner body fixed within said outer body and having a hollow shaft with its opening alined with said central openings, said inner body having a pair of recesses,

a ratchet wheel mounted in one of said recesses with its rotational axis parallel to and spaced from the axes of said openings and having an indentation on its outer periphery, said ratchet wheel having a passageway rotatable into alinement with said openings and said primer cup,

a detonator mounted in said passageway,

a pin resiliently biased into said indentation in a direction substantially normal to said rotational axis and engaging the rear surface of said indentation with a force such that it is locked thereto only during a setback force incident to the firing of said shell and is thereafter withdrawn therefrom by the centrifugal force incident to the rotation of said shell,

an inertia disk oscillatable about said hollow shaft and having a slot and an opening both spaced from its rotational axis,

a fixed stop pin extending through said opening, and

a pawl having a tang engaging said slot and driven by rotation of said ratchet wheel to oscillate said disk and predetermine the time between the withdrawal of said pin from said indentation and the alinernent of said detonator with said primer cup.

2. In a fuze arming device which is combinable with a shell and is adapted to be set into rotation by the firing of said shell from a rifle, the combination of means forming a housing having at its opposite sides openings which are alined and are concentric with the rotational axis of said device,

a primer mounted in one of said openings,

an unbalanced ratchet wheel having an indentation in its outer periphery and rotatable in said housing about an axis displaced from the rotational axis of said device,

an inertia disk pivoted about the rotational axis of said device,

a pawl reciprocated by said ratchet wheel and having a tang engaging a slot in said disk,

a stop extending through a hole in said disk for limiting oscillation of said disk by said pawl,

a detonator normally supported by said ratchet wheel in a nonregistering position relative to said primer,

a pin alined with said indentation and supported by said housing in a position to be withdrawn therefrom by the centrifugal force incident to the rotation of said device, and

means biasing said pin into said indentation whereby the setback force incident to the firing of said shell produces between said pin and the Wall of said indentation a frictional engagement which counteracts the effect of said centrifugal force on said pin until the decay of said setback force and permits the movement of said detonator into alinement with said primer upon said decay.

References Cited in the file of this patent UNITED STATES PATENTS 

